1,720,980 research outputs found
Insight into the mechanisms of the multicomponent Ugi and Ugi-Smiles reactions by ESI-MS(/MS)
No full textThe mechanisms of the Ugi and Ugi–Smiles reactions were investigated by using finely selected reaction conditions that allowed all of the intermediates to be “fish-out” and characterized by ESI-MS/MS. New insight into the Ugi and Ugi–Smiles reaction mechanisms is provided without using charge-tagged reagents. Characterization of the isomeric species of the Mumm rearrangement in the gas phase was performed by using MS/MS
Biomasse lignocellulosiche per biocarburanti di seconda generazione: una panoramica
No full textSecond generation bio-fuels derive from non-food parts of the plant. The most critical step in their production is the isolation of fermentable monomeric sugars from ligno-cellulosic biomasses since they contain the sugars polymers (cellulose and hemicelluloses) strongly embedded in lignin. For this reason hydrolysis of sugars polymer requires necessarily pre-treatments to eliminate lignin from biomasses and allow sugars polymers hydrolysis
Volatile compounds of ex vitro and wild plantlets of<i>Artemisia umbelliformis</i>subsp.<i>eriantha</i>(Apennines’ genepì)
No full textThe mountain area features (steep slopes, shallow soils and low temperatures) are often unfavourable to the agricultural activities. Therefore, it is mandatory to develop strategies which are sustainable under the environmental and economic point of view. The experience gained over the last ten years has allowed us to carry out a project called “2013-2015 New Plants” addressed to the protection and the valorization of a high altitude sub-endemic species of our area, Artemisia umbelliformis subsp. eriantha, commonly named “genepì”. This project aims at producing a valid alternative to illegal harvesting of wild individuals and allowing the development of the production chain. In summer 2014, ex vitro plantlets of a selected clone of A. umbelliformis were transferred to experimental fields characterized by eight different altitudes. Volatile compound profiles of micropropagated plants were evaluated in comparison to the profiles obtained from fresh and dried leaves of wild-plants (W) using headspace-solid phase microextraction gas chromatography mass spectrometry (HS-SPME-GC-MS). The chromatographic profiles appear to be qualitatively similar between wild plants and in vitro-produced plantlets, with amounts of the characteristic thujones at about 60% of total volatile compounds. HS-SPME-GC-MS data showed the possibility of differentiating scent blends of genetically identical plants, and even flowers and leaves from the same individual
Characterization of the Volatile Profiles of Insect Flours by (HS)-SPME/GC-MS: A Preliminary Study
Full text linkThe growing world population, combined with scarcities of agricultural land, water, forest, fisheries, and biodiversity resources, makes it necessary to search for alternative sources of nutrients. For this reason, in recent years, edible insects have been introduced into the diet, even in areas where entomophagy is not traditional. In light of this, the present study aims at characterizing the aromatic profile of three edible insects flours: cricket (Acheta domesticus, CP), buffalo worm (Alphitobius diaperinus, BW), and mealworm (Tenebrio molitor, MW). This goal has been achieved by means of an (HS)-SPME/GC-MS strategy. 67 compounds have been tentatively identified; of these, 27 are present only in the CP and BW flours, while 10 are common in all three flours. The compound with the highest peak’s relative area in gas chromatograms of CP and BW flours is hexadecanoic acid, while in MW it is 1-heptylpyrrolidin-2-one. In general, we have observed that CP and BW flours have 37 compounds in common, and their volatile compositions along with their profiles are more similar to each other than to MW profile
Volatile fingerprints of artemisinin-rich Artemisia annua cultivars by headspace solid-phase microextraction gas chromatography/ mass spectrometry
No full textThe cultivar Anamed (A3) is a hybrid of Artemisia annua with a high content of the secondary metabolite artemisinin,
a well-known antimalarial drug. Here we report for the first time the volatile profile of fresh leaves of this hybrid in
comparison with that of Artemisia annua L. wild-type species. Evaluation and comparison of the volatile profiles of
A. annua genotypes with different content in artemisinin were carried out by headspace solid-phase microextraction
(HS-SPME) coupled with gas chromatography/mass spectrometry (GC/MS) that was performed on fresh leaves of the
plants under investigation using a polydimethylsiloxane (PDMS) fiber. The chromatograms obtained from hybrids
with a high content of artemisinin (A. annua cv. Anamed A3 and A. annua cv. Artemis F2) reveal the total absence
of artemisia ketone, one of the major and characteristic compounds of the wild-type A. annua L., along with a
significantly lower variety of volatile compounds. In conclusion, HS-SPME coupled with GC/MS is a very useful,
non-destructive and efficient method to describe the volatile pattern of Artemisia annua cultivars. It represents a
rapid screening method for the evaluation of volatile biomarkers like artemisia ketone, whose absence is typical
of artemisinin-rich A. annua cultivars
Volatiles fingerprints of Artemisia umbelliformis subs. eriantha by headspace-solid phase microextraction GC-MS
No full textArtemisia umbelliformis subsp. eriantha is a protected species, whose essential oil is used in liqueur industry. Volatile profiles of fresh leaves and flowers from wild plants in comparison with regenerated in vitro plants introduced in experimental fields within an Italian national park were evaluated by headspace-solid phase microextraction gas chromatography mass spectrometry (HS-SPME-GC–MS). The chromatographic profiles appear to be qualitatively similar. The content of thujones, the characteristic metabolites of this species, is comparable with that obtained by analysis of essential oils. Principal component analysis of the HS-SPME-GC–MS data supports the possibility of differentiating scent blends of genetically identical plants, and even flowers and leaves from the same individual. HS-SPME-GC–MS is shown to be a very efficient method to analyse and to describe the pattern of components of A. umbelliformis subsp. eriantha cultivars’ scents. It represents a rapid screening method highlyrecommendedforthestudyofprotectedspecies,becauseitisnon-destructiveandit only requires small amounts of fresh material
Classification of “Ricotta” whey cheese from different milk and Designation of Origin-protected samples through infrared spectroscopy and chemometric analysis
Full text linkWhey cheeses are produced in various parts of the world, such as Portugal, Spain, and Turkey. In Italy, whey cheese goes under the name “ricotta”. This study investigates the classification of ricotta whey cheese derived from various milk sources (either protected designation of origin (PDO) or not) using an Attenuated Total Reflectance Fourier-transform infrared (ATR-FTIR) spectroscopy combined with chemometric analysis. Employing the SPORT-LDA method, which can incorporate Variable Importance in Projection (VIP) analysis, 287 samples of ricotta cheese produced using milk from four different animals (sheep, cow, goat, and water buffalo) were classified according to the animal origin. This led to the correct classification of 97 % of the test samples (3 misclassified samples over 97). VIP analysis revealed that the spectral ranges of 3300–3100 cm−1, 2900–2800 cm−1, and 1700–1300 cm−1 are consistently relevant across all milk sources, thanks to the key molecular vibrations associated with protein structures, lipid content, and water. Eventually, the analysis was circumscribed to sheep ricotta cheeses, because some of these present the PDO quality mark. SIMCA was used to classify PDO samples with respect to the Non-PDO sheep ricotta individuals. The application of SIMCA to model class PDO led to 82.1 % of sensitivity and 82.7 % of specificity (in external validation). The findings underscore the robustness of ATR-FTIR spectroscopy and chemometrics in maintaining the integrity of PDO products and ensuring quality control
Exploring the frontiers of synthetic eumelanin polymers by high-resolution matrix-assisted laser/desorption ionization mass spectrometry
No full text"New trends in material science and nanotechnologies have spurred growing interest in eumelanins black insoluble biopolymers. derived by tyrosinase-catalysed oxidation of tyrosine via 5,6-dihydroxyindole (DHI) and its 2-carboxylic acid (DHICA). Efficient. antioxidant and photoprotective actions, associated with peculiar optoelectronic properties, are recognised as prominent. functions of eumelanin macromolecules within the human and mammalian pigmentary system, making them unique candidates. for the realisation of innovative bio-inspired functional soft materials, with structure-based physical–chemical properties. An unprecedented. breakthrough into the mechanism of synthetic eumelanin buildup has derived from a detailed investigation of the. oxidative polymerization of DHI and its N-methyl derivative (NMDHI) by linear and reflectron matrix-assisted laser\/desorption ionization. mass spectrometry. Regular collections of oligomers of increasing masses, spanning the entire m\/z ranges up to 5000 Da. (>30-mer) and 8000 Da (> 50-mer) for the two building blocks, respectively, were disclosed. It is the first time that the in vitro polymerisation. of dihydroxyindoles to form synthetic eumelanins is explored up to its highmass limits, giving at the same time information. on the polymerisationmode, whether it follows a stepwise pattern (being this the conclusion in our case) or a staking sequencing. of small-sized entities. It also highlighted the influence of the N-methyl substituent on the polymerization process; this opens theway. to the production of N-functionalized, synthetic eumelanin-inspired soft materials, for possible future technological applications
Mild catalytic oxidations of unsaturated fatty acid methyl esters (FAMEs) by oxovanadium complexes
No full textA selection of unsaturated fatty acid methyl esters, namely methyl oleate (C18:1), methyl linoleate (C18:2) and methyl linolenate (C18:3) has been oxidized under mild homogeneous catalytic conditions, using a series of oxovanadium(IV) complexes containing 4-acyl-5-pyrazolone donor ligands with different substituents on acyl residue. The main goal was to evaluate the catalytic role exerted by oxovanadium(IV) metal center, as precursor complex, in the selective oxyfunctionalization of carbon-carbon double bonds of these bio-renewable resources, as a greener alternative to more drastic processes currently used at the industrial level. The three substrates, oxidized using tert-butylhydroperoxide as main oxidant, with or without solvents, showed high conversions of starting materials and high selectivities in the formation of corresponding mono- di- and tri-epoxides, especially under solvent-less conditions. Investigations on a probable catalytic cycle mechanism operative in the tert-butylhydroperoxide oxidation of a simple FAME model substrate, have been performed by means of ESI-MS
Protein Secondary Structure Patterns in Short‐Range Cross‐Link Atlas
Full text linkCross-linking mass spectrometry (XL-MS) has become a powerful tool in structural biology for investigating protein structure, dynamics, and interactomics. However, short-range cross-links, defined as those connecting residues fewer than 20 positions apart, have traditionally been considered less informative and largely overlooked, leaving significant data unexplored in a systematic manner. Here, we present a system-wide analysis of short-range cross-links, demonstrating their intrinsic correlation with protein secondary structure. We introduce the X-SPAN (Cross-link Structural Pattern Analyzer) software, which integrates publicly available XL-MS datasets from system-wide experiments with AlphaFold-predicted protein structures. Our analysis reveals distinct cross-linking patterns that reflect the spatial constraints imposed by secondary structural elements. Specifically, α-helices exhibit periodic cross-linking patterns consistent with their characteristic helical pitch, whereas coils and β-strands display nearly monotonic distributions. A context-dependent protein grammar reinforces short-range cross-link specificity. Short-range cross-links can enhance the statistical inference of secondary structures within integrative modeling workflows. Additionally, our work establishes a framework for benchmarking AlphaFold's local prediction accuracy and provides novel quality control criteria for XL-MS experiments. We anticipate that X-SPAN and our short-range cross-link database will serve as a valuable resource for exploring local secondary structure rearrangements and their potential roles in protein function and allosteric regulation
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